Tire building drum



May 28, 1935. A.E. BENSON h 2,002,687

TIRE BUILDING mum Filed Oct. 11,1933

INVENTOR.

flRrm/R E. .Bsus on.

A TTORNE Y.

Patented May 28, 1935 I 2,002,687

A ENT Arthur E. Benson, Indian Orchard, Mass, as-

signor to The Fisk Rubber Corporation, Chicopee Falls, Mass, a corporation of Delaware Application October 11, 1933, Serial No. 693,185

2 Claims. (Cl. 154-9) This invention relates to annular tire buildished tire. By bead hinge is meant the zone in ing drums of the semi-flat type; that is, to which the stiffness of the bead construction is drums in which the portion between the bead graduated into the flexibility of the carcass. In

receiving portionshas a radius greater than the the drawing the crown height is indicated by 5 bead radius but less than the crown radius of the line H, parallel to a line drawn through the 5 the completely shaped tires. bead positions and spaced therefrom a distance The object of the invention is to provide ah which is'the measure of the crown height of drum of the semi-fiat type affording more unithe drum. form building conditions and greater facility in In laying out the drum of my invention, cir- .l0 shaping the carcass material to' the drum. .cles A of predetermined radius a are drawn These and further objects will be more specifiwith their centers spaced the predetermined 7 cally disclosed in the following specification and distance 13 plus 2a and circles C of predeterclaims. mined radius 0 are drawn all in accord with r In the accompanying drawing, which illusthe desired tire size and bead construction. The

l5 trates one embodiment of the invention, line H is laid out to give the desired crown 15 Fig. l is a side elevation of a building drum height. The profile of the intermediate portion according to the invention; of the building surface of the drum is then con- Fig. 2 is a sectional view, on a larger scale, structed by drawing a circular arc tangent to substantially on line 22 of Fig. 1;. and circlesC and to line H, by well known methods,

Fig. 3 is a sectional detail showing the manner the are R having a mathematically determined 20 of effecting adjustment of the drum for a limradius r. .The result is a drum profile providited range of tire sizes. ing bead seats I l, shoulder portions I2 for shap- The drums now in use have proved unsatising the tire up to the bead hinge and an interfactory for the construction of tires having a mediate portion I3 extending between said very large cross-section in comparison with shoulder portions in a single circular arc. 25 their bead diameter, such for example as a With a drum constructed as above described, 7.50/17. In tires of this character the excessive the stretched band of carcass material contracts skirt of the carcass plies can be condensed and over the central part of the portion l3, as indi-- shaped to the conventional semi-flat drums only cated diagrammatically in dotted lines at H,

80 with the greatest diflicultyif at all. I have the cords tending to change their angle in acovercome these difiiculties by so shaping the cordance with the decrease in diameter. Due to drum surface, as later explained, that the work the arcuate profile of the drum, the mechanical of condensing the skirts of the plies is greatly shaping and contracting of the free skirt porfacilitated, and the change of cord positions in tion [5 (shown in dotted line) to the remaining the subsequent expanding of the tire to tire portions of the drum are merely a gradual 35 shape is so graduated that excessive cord movecontinuation of the shaping and contraction ment does not take place, although no comwhich automatically takes place in the portion plete shaping of the carcass above the beads l4, the degree of angle change increasing conwhile the carcass is on the drum is resorted to. stantly but uniformly as the shoulder portions Referring to the drawing, the drum generally, are approached; the work of mechanically shap- 40 indicated at I0, is provided with concave, wideing the carcass material to the drum being ly spaced bead positioning grooves or seats H, greatly facilitated by the initial automatic conhaving a radius a, the distance between the bead traction and the substantially uniform increase seats being indicated at 1). Immediately above in degree of angle change to the shoulder por- 5 the bead grooves H the drum surface is curved tions I2. outwardly, upwardly, and then inwardly to form Within reasonable limits tires of the same bead hinge portions or shoulders l2. The porbead diameter but of larger cross-section can tions [2 in sectional profile are preferably circube accommodated on a given drum by cutting lar arcs of a radius 0. The values of a and c the drum circumferentially at its crown as inwill vary with the bead construction used and dicated at I 6, to permit insertion of spacing will be determined for a given drum by the premembers ll, as shown in Fig. 3, the width of ferred practice of bead construction with respect members l1 being such as to bring distance b to the character, number, and size of the nonto the desired value. extensible elements incorporated in the bead It will be understood that the drum is cut and the position of the bead hinge of the fintransversely, as at H! in Fig. 1, into segments 5 to permit collapsing of the drum in accordance with approved practice.

Having thus described my invention, I claim: 1. An annular tire building drum of the semifiat type having widely spaced bead receiving grooves, curved shoulder portions positioned above the bead receiving grooves for shaping the tire carcass adjacent the bead hinges, and

an intermediate portion extending between said shoulder portions in a single circular arc tangent to the curve of the shoulder portions and; tangent to the line defining the maximum crown height of the drum.

line defining the maximum crown height of the 10 drum.

ARTHUR E. BENSON. 

